Method of making sulphuric acid from waste materials



March, 1938. P. J. HARRlNGToN ET AL 2,110,257

METHOD OF MAKING SULPHURIC ACID FROM WASTE MATERIALS Filed oct. 7, 19352 Sheets-Sheet l Q Nw @sm QW wh' WGQSOR UWM/lm March 8, 1.938 P. J.HARRINGToN-ET AL 2,110,267

METHOD OF MAKING SULPHURIC ACID FROM WASTE MATERIALS 2 Sheets-Sheet 2Filed Oct. 7, 1935 muv NN. QN

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UNITED STATES PATENT oi-EicE METHOD or mimic suu'nmuc :soin mou wAs'rEManzanas Paul J. Harrington, Westileld, and Harry G.

Burks, Jr., Elizabeth, N. J., assigner: to-Standard Oil DevelopmentCompanxa corporation of Delaware Appiiooiion october v, 193s, seria No.692,590

` a claim. (ci. zs-i'z'n This invention relates to improvements in theFig. 2 is a detail sectional view showing a premanufacture of sulphurdioxid, sulphur trioxld, ferredform 'of air and fuel inlet to theretort; sulphuric acid and the like, from sulphur or sullIiig. 3 is afragmentary side elevation, partly phur compounds contained in wastematerials, in section, of an installation using recirculation 5especially from sulphur-ic acid in the sludge deof SBS thi'Oiigh 8-IlOn-rotary retort and showing 5 rived from the reilning of hydrocarbonoils with also agitating means `in the retort; and that acid. Petroleumacid sludges are produced Fig- 4 is e Similar View 0f a Vertical ret0rt.in great quantities. They are a potential source Referring ilrst to Fig.1, reference numeral I of suilicient sulphuric acid to satisfy a largepart designates a tubular retort, for example about i of the reneriesrequirements, but the diillculty thirty feet in length and mounted forrotation. 10

of handling the sludges often causes them to be The retort preferablyhas insulating and reregarded es mer'eiy obnoxious waste materials,fractory materiell coveringits inner wells. Acid adapted at best onlyfor use as low` grade fuel. Sludge t0 be treated iS Supplied t0 theretOrt at They often raise serious problems of disposal. its upper endthrough a conduit I from supply l5 A principal object of the inventionis to protank l. Oxygen-containing gas (generally air) 15 vide adecomposition method for the emcient dislS Supplied in any Suitablemanner through a posal of`acid sludges, while at the same time header 5in which there is a valve 6. A header preparing a good grade ofconcentrated or fuml, in which there is a valve 8. Serves fOr the edingsuiphurio eoid, or other usefu1 sulphur derivmission of combustible ses.Branch lines e. I0.'

atives, and conserving the fuel value of the il and l2. I3, Il. eenneetthe headers 5 end 7 20 sludge. Several types of equipment which mayrespectively with the distributor nozzles I5, IB be advantageously usedin carrying out the procand Il in the retort. Valves are provided in theess also form e part of the invention, but this is branch lines sothatthe proportions of air and not necessarily limited to the forms ofapparatus eOmbllStlble 86S een be adjusted aS desired. The

shown. In general, the principle of operation is air-fuel lines extendthrough a fixed head I8 25 the concurrent ow of the acid sludge with a011 the end 0f the retort This head engages .a current of hightemperature gas, preferably oxyneck I9 and the neck is freely rotatablein the gen, air or other oxygen-containing gas, with or head. Suitablegaskets and securing means are without combustible. gases or other fuel.The provided in the `well-hncwn manner to make 3o reaction is carriedout under conditions to conthe Joints fluid tlEht- 30 vert at least partof the carbonaceous matter of The preferred form 0i' nozzlelsillustrated in the sludge into coke or semi-coke and to reduce Fig. 2in which I5a denotes the nozzle itself. 9G the sulphurio acid to sulphurdioxid. The oxythe outer pipe which receives -fue1 ses fromgen-containing gas is supplied in increments to branch line 9b, and |26the inner pipe Which the charge of sludge as it proceeds through thereceives oxygen-containing ses frombranch line reaction vessel. I2b. Thevalves 9c and I2c in these branch lines Many processes of handiing acidsludge have a're preferably automatically operated by a pybeensuggested, including some 1n which the sul- I'Ometer and mOtOr hook-upas indicated by 20.

phuric acid of the sludge is converted into sul- The same nozzle may beused when high tem- 40 phur dioxid by concurrent now of the sludge withperature sas is used without combustion. In 40 hot oxidizing gas,followed by the catalytic conthat case one of the pipes 9a, I2a may beclosed. version of the resulting sulphur dioxid into sui- Other forms oinozzle and supply pipes may be phur trioxid. vIn the present invention,the inadopted. provided they meet the essentiel concremental addition ofthe oxidizing gas makes ditions of supplying the gases to the retort atpossible the full utilization of the fuel value of properly spacedpoints and at the desired tem- 45 the sludge (including usually theavoidance of perature. outside separate generation of hot gases) and theRetort I is mounted for rotation in any suitable heat is controlled moreaccurately than has hereway, as by the gear-toothed bands A2i and I!tofore been possible. meshing with gears 23 and 24. The driving forceThe invention will be fully understood from the is supplied for exampleby a motor 2B through 50 following description, read in connection withreduction gears 28. y the accompanying drawings, in rwhich The gaseousand vaporous product of reaction Fig. 1 is a side elevation, partly insection, of in retort I is discharged through line 21 into a apparatusin which the sludge is fed through a tower 28 supplied with coolingwater at the top rotary retort; through line 20. A portion of the watermay be 55 with the retort is through a Joint Ila, IIa as del scribedabove.

When a petroleum acid sludge and air` are the reactants, the gaseous andvaporous product` will be in the main sulphur dioxid, steam, carbondioxid, oil, and nitrogen. Most of the steam and heavy oil are condensedin tower Il. 'lhe condensate is withdrawn through line Il. The residualgas may contain traces of oil or otherv -impurities and is thereforebest further treated,

as by scrubbing with oil in tower It to which the gas is conveyed byline 8l. lhe oil used is preferably heavy gas oil or the like. It issupplied through line Il and withdrawn through line Il by pump Il to thestripper Il. From this the stripped oil passes back to the tower 8l.Light oils are removed from the stripper by line Il. Spent oil is drawnoii through line 4I when desirable.

lhe purified sulphur dioxid and accompanying nitrogen or othernon-reactive gas are passed into the conversion stage, indicateddiagrammatically by I2, through a line 43. Although the invention is notrestricted to any particular form of conversion, the vanadium pentoxidecatalyst method is recommended. 'I'his is well lknown in the art. Thesulphur trioxid produced is withdrawn through line u for the manufactureof furning sulphuric acid, or acid of any other desired concentration.It willl be understood that sulphur dioxid may be recovered as such orconverted into other products than sulphurlc acid.

The solid or semi-solid product of the reaction in retort i is withdrawnthrough a conduit 4I connected to head ila and discharging into achamber Il in which a screw conveyor l1 works. 'I'he coke -withdrawalsystem. is kept closed against escape of gas as by actuation of siidevalves in the well-known manner. 'Ihe retort may be run to give variousqualities of coke or coky material, ranging from a semi-coke which isthe carbonaceous matter of the sludge without great modincation, to dry,granular carbon. 'lhe material produced may be handled con. veniently.'lhe elimination of most of the sulphur content ss sulphur dioxid avoidsone objection to the use of acid sludge as a fuel and the form of thecarbonaceous product is much bet.

ter adapted for fuel than the original sludge.

' The usual charge material for the process is a white oil sludge, suchasis obtained in the rening of petroleum oils for the manufacture ofheavy medicinal oils and the like. Such sludges ordinarily yield onheating about 24% water, 40% solid carbonaceous or coky matter, 1 to 2%oil and about 33% sulphur dioxid combined as sulphuric acid and othersulphur compounds. Another typical material to be treated is naphthasludge which has a lower 'acid content. 'I'his type of sludge also has ahigher oil content than white oil slud'ge. Sludge acids, acid oils, andother waste sulphuric products may also be treated. The gaseous productobtained is ordinarily sulphur dioxid carried by a substantially largervolume of combustion products and nitrogen. However, by using arecirculation method, such as will be described. it is possible to raisethe sulphur dioxid content to any desired value, even as much as or 90%.

In order to obtain the desired reaction in the retort I. it is necessaryto make sure that the oxygen content is not too great. a large excessThe tcwer has baffles I2 or other suitable of oxygen will result in theproduction of sulphur trioxid, which will seriously disturb theoperation of the catalytic converter. On the other hand, there must beenough oxygen present to support the combustion oi sludge material (oraddedcombustible) so that the temperature in the retortwill besumciently high.` Most of the sulphuric acid, in an emcient operation,must be reduced to sulphur dioxid by heat and in the presence .ofcarbonaceous material. A proper balancebetween these two extremes can bereadily obtained by adjusting the valves in the -air and fuel lines0,10, il'and if, il, Il.

v duced. Insomecasesitwillthenbeunnecessary to supply combustible gaseswith the oxygen-con-l taining gas to all the zones of the converter. The

" coke usually is not heated to above 40o-800 Il'.

Pyrometers are placed at numerous intervals along the retort so that theoperator can determine the temperature conditions and produce morecombustion in any zone which requires additional heating, or reducecombustion in any Vzones which tend to be overheated. Automaticallycontrolled valves are preferably used, actuated by the retorttemperatures.

Referring to Fig. 3, the device illustrated is similar to that shown inPig. l, but a non-rotary retort is used and provision is made for therecirculation of gases produced in the retort so as to build up a highconcentration of sulphur dioxid in the gases. In this ngure, referencenumeral l! indicates the retort which is mounted on a suitable setting6. 'Ihe stirrer or agitating device 41 extends 'longitudinally throughthe retort and has arms which are so arranged as to scrape oif thedeposits of coke or coke-like material which may tend to form on thewalls. The arrangement for introducing the air, with or withoutcombustible gas, may be the same as is shown in liigs. 1 and 2.

The gaseous reaction product is withdrawn through la line 40 which leadsthrough a blower I0 into a reheater Il, heated by burner Il.

From the reheater a line Il' is extended to connect with the inlet lineM which supplies the air to the distributor pipes.

There is a drawoff line 8l connected to the line 'Il and through thisdrawoif line some or all of the `gaseous product of reaction in retortIl may be withdrawn. Valves Il and l1 permit the operator to control theilow of gases through these lines. By the arrangement described it ispossible to secure any desired concentration of sulphur dioxid in thegas passing from the retort to the catalytic converting chamber or otherplace of disposal. In order to vent the system a pipe Il controlled byvalve I9 is provided at a suitable point, for instance on the line 5I.

It will be noted that the present invention does not require the use ofa furnace to develop gases at extremely high temperatures. If all theheat required for converting the sulphuric acid to sulphur dioxid were'supplied 4from an external source in the form of hot gases, those gaseswould have to be at a temperature very close to 2000 F. Furnaces forgenerating gases .at this temperature are costly and require frequentrepairs. In the present method the required heat is produced byfdirectcombustion in the sludge itself. For the most part the fuel is thecarbonaceous matter of the sludge, only such additional combustiblebeing added as is requiredby special circumstances.

Although inthe foregoing description reference has been made to rotatingretorts or retorts which are provided with agitating devices,

in some cases it is possible to operate with-a degreeof satisfaction bysimply passing the acid sludge and the oxidizing gas concurrentlythrough a non-rotary, nonagitated retort, for example, a.vertical-retort 60, as shown in Fig. 4.

In this gure the nozzles 6l, 62, 63', 64 are provided. The acid sludgeor other sulphur-containing waste material is fed in through line 65.The sulphur dioxid is removed through line 66V and the coke by conveyor61. The recovery sys'- tem is as described.

For some purposes it is satisfactory to expel a part only of the sulphurdioxid and this canbe l such gas with a greater quantity of oxygen-intodone without coking the sludge.

In the preferred method of operation a rotary or stirred retort is usedand the oxygen-containing gas is supplied so that near the inlet of theretort there will be some combustion but no high temperaturedevelopment. In the intermediate zone the quantity of oxygen should besuch as to effect combustion ofvv the oil vapors generated in theretort. In the nal stageapproaching the outlet of the retort thereshould be a small excess of oxygen'. If there is too much engen, thetendency to form sulphur trioxid is pronounced, and this is to beavoided, since it disturbs the operation of the catalytic converter. Onthe. other hand, someoxygen is required to prevent the for mation ofhydrogen sulphide. It is not possible to state exactly what temperaturesshould prevail in the various sections of the retort, asthesetemperatures will vary with the particular sludgeand the desired extentof decomposition. By way of example, however, when treating white oilsludge weprefer to maintain a temperature of about 1600 F. in theoutlet'end of the retort, 1400" F. in the intermediate sectionl and 500F. 'in the inlet section. In general the .temperature should riseprogressively toward the outlet.- VOperation at substantiallyatmospheric pressure is in general satisfactory but pressures higher orlower than atmospheric may be used if special circumstances requirethem.

It willbe understood that stirring or agitating means may be used inarotating retort. Also,

adopted in the devices of Figs. 1 and 4. When high temperaturenon-oxidizing (or substantially non-oxidizing) gas is used, it will b esupplied at temperatures suiiiciently high to maintain the re bustion.However, it is preferred, as noted above,

to derive all lor most of the heat fromthe burning of the sludgeitself.-

Various changes and alternative arrangements may be made -withinthescope of the appended claims, in which it is our intention to claim allnovelty inherent in the invention, as broadly as the prior art l 1.Method of producing sulphuric acid. fromv petroleum acidsludge,comprising passing 'the sludge concurrently lWithu'hot oxidizinggas through a vreaction zone, introducing such gas' into the 'rst stageof thereaction zone toproduce a moderate. temperature therein,introducing.'

an intermediate stage oi' the reaction zone to produce a hightemperature therein to cause liberation of sulphur` dioxid, introducinginto the last stage of the reaction zone a gas containing onlya smallamount of oxygen in excess of vthat which will be consumed, withdrawingthe gaseous reactionproduct containing sulphur dioxid, and

' converting the sulphur dioxid into sulphuric acid.

sludge, a 4stream of an oxidizing gas, projecting quired retorttemperatures without internal comanother Aincrement of said gas streaminto the-v sludge atan intermediate stage to further heat the sludgeto'la decomposition temperature, and projecting a third increment ofsuch gas in a nal stage oi' thepassage through theretort, taking off thenonreactive gases and the sulphur dioxicl produced `by. the reactiontogether with oil vapors and steam, condensing the oil vapors and steam,and'passing the residual sulphur dioxid and nonreactive gases to acatalytic vconversion zone.

3. Method according to claim 2, in which the gaseous product of thereaction is recirculated at least in part through the retort, whereby aconfor ready conversion to sulphur trioxid in the centration of sulphurdioxid is obtained adapted

